After ex-husband Charlie Sheen’s angry tirade against her on Twitter, Denise Richards has reportedly upped the security at her home, according to Popeater.

"She wants [daughters] Sam and Lola to have normal lives, but after the recent threats and verbal attacks, she has increased her security,” a source says. “When you are dealing with a madman, it's better to be safe than sorry."

Sheen’s over-the-top behavior on Twitter reportedly has Richards worried. "Denise has learned how to deal with the name-calling, but once you start tweeting pictures of yourself with knives and saying you wished someone would die it's a totally different game," the source says. "Denise is no longer angry — she's scared."